[Coco] Need new disk drive...

[Chuck Youse]

On Thu, 2008-09-18 at 08:04 +0100, Phill Harvey-Smith wrote:
> Gene Heskett wrote:
> > On Wednesday 17 September 2008, Chuck Youse wrote:
> >> On Wed, 2008-09-17 at 21:25 -0400, Gene Heskett wrote:
> >>> That controller MAY have a Fujitsu 8877 FDC chip in it.  This chip is one
> >>> of the few that can be used at 500 kilobaud data rates, allowing DSDD
> >>> floppy drives to be used at 1440 kilobyte size.
> >> Am I missing something?  Double-sided double-density 5.25" drives are
> >> 360K, no?
> >>
> > If set for 40 tracks, double sided in the os9 descriptor then yes. 
> 
> <pedantic mode>
> Or 80 track single sided.....as IIRC some early Atari ST machines used, 
> at least here in the UK.
> </pedantic>
> 
> >                                                                But I 
> > believe that chip can have the high speed data rate hack applied, which means 
> > the nearest $25 3.5" 1.44 meg drive with HD diskettes can be used in it.
> 
> But then wouldn't that be DSHD ? Double sided, High density ? Was this 
> what was sometimes refered to as Quad density, or was that 80 tracks as 
> opposed to 40 ?

"Quad density" (a misnomer, of course) 5.25" drives were 80 tracks,
double-density.  720K per diskette.. not too common, but I remember the
Tandy 2000 had 'em.

C.